Automatic roof vent



May 17, 1966 E. SHAPIRO 1,

AUTOMATIC ROOF VENT Filed June 1'7, 1963 5 Sheets-Sheet l INVENTOR ATTORNEY 3 Sheets-Sheet 2 Filed June 1'7, 1963 INVENTOR ATTORNEY May. 17, 1966 E. SHAPIRO AUTOMATIC ROOF VENT 3 Sheets-Sheet 5 Filed June 17, 1963 Z 0 7% E 4 a 4 a a A. 3 l v f C K Y 1 L i 9 4 llllL MW .0 \I l \x m 49. 1 ix i u b 2 w a n 5 w m 8 2 7 a 5 a w 9 m H 0 3 6 m 8 A A 3 y W I Q 0 7 aw J 3 INVENTOR rom ATTORNEY United States Patent 0 3,251,158 AUTOMATFC ROOF VENT Eli Shapiro, Dallas, Tex, assignor to Plastic Products of Texas, IIKL, Dailas, Tern, a corporation oi Texas Filed June 17, 1963, Ser. No. 288,380 16 Claims. (CI. 52-41) This invention is concerned with a roof vent, and is particularly concerned with a vent having a cover which automatically opens in response to heat or pressure within a building.

The improvement comprehended in the subject matter of this invention is particularly related to a covered vent which may be installed in the roof of a building over an opening provided in the roof, and the cover thereon is arranged to automatically open when the heat or pressure within the building rises to predetermined levels so as to allow the escape of heat, smoke, and gases from the building in the event of a fire or explosion therein. In the event of an explosion the vent is automatically opened to relieve the pressure therein, and thus prevent the building from being blown apart.

The vent cover is also arranged to be manually released for opening in the event same is desirable.

It is desirable to have openable vents or sky lights in the roofs of buildings, such as commercial buildings, factories or warehouses, so that in the event of fire, explosion, or the release of noxious fumes within the building, the vents can be opened to allow the escape thereof so as to permit firemen to more readily gain access to the source of fire, prevent sufiocation of firemen or personnel, and prevent explosions and undue damage to the contents of the building. 7

The present invention is addressed to that type of automatically openable vent cover wherein the door or cover is hingedly attached over an opening through the roof, and the cover is held closed by a spring-urged latch member which is released by the parting of a fusible link when subjected to a predetermined temperature. The release of the latch mechanism allows a spring actuated lever mechanism to become operable to lift the vent cover and thereby open the vent.

The latch mechanism may also be disengaged by a predetermined pressure within the building being exerted against the cover to thereby allow the spring-lever mechanism to become operable to lift the cover.

A separate latch means is provided for engaging one of the lever arms of the spring lever mechanism, to automatically latch the cover in open position when it is raised.

Manual means is also provided for releasing the latch member holding the cover down, which is accessible from inside the building, or it may be arranged to be accessible from the roof of the building, so that the roof vents may be opened for venilation purposes, or for releasing smoke or noxious gases from the interior of the building, even though the heat and pressure is not sufficient to automatically release the latch.

Vent covers have heretofore been known in the art which are held closed by a latch, cord or other apparatus released by the parting of a fusible link. However, such devices were generally unsatisfactory because of various objections, such as the fact that the fusible link was atlatched directly to the spring lever mechanism which opened the vent in such a way'that excessive force was exerted against the fusible link to cause its premature breakage. Furthermore, such devices were not operable in response to pressure, and were not easily operable by manual means.

In the device disclosed herein, the latch-fusible link mechanismhas no connection with the spring lever mechanism which raises the vent cover, and therefore may be set to release at any desired temperature or pressure. Upon the parting of the fusible link, a relatively small mechanical force is required to release the hold down latch in response to the force of the spring lever mechanism, and the spring setting of the hold down latch mechanism is of such value that the latch may be easily disengaged by manual means.

It is, therefore, a primary object of the invention to provide an automatic vent cover actuating mechanism which is responsive to both predetermined heat and pressure.

A still further object of the invention is to provide an automatic vent cover opening mechanism, wherein the vent cover is automatically latched in raised position.

Still another object of the invention is to provide an automatic vent cover opening mechanism wherein the latch means holding same in closed position may be adjusted to release at any desired temperature or pressure, and which may be easily released by manual means.

A still further object of the invention is to provide an automatic vent opening device wherein a plurality of spring lever mechanisms may be provided, as desired, for opening vent covers of various dimensions and weights. This is made possible by reason of the fact that the latchfusible link arrangement for holding the vent cover down ward, is not associated in any manner with the spring lever mechanism for opening the vent cover.

A still further object of the invention is to provide automatically actuated vent cover mechanisms which are simple and easy to reset after being actuated.

Another object of the invention is to provide apparatus for automatically opening a vent cover wherein the spring lever mechanism for raising same, is entirely outside of and above the vent after the vent lid has been raised so that it does not form an obstruction to the flow of heat and gases therethrough, and is not subjected to damaging heat when the vent has been opened.

A still further object of the invention is to provide mechanism for automatically opening a vent cover which is simple and economical in construction, and positive in its action.

Other and further objects of the invention will become apparent upon reading the detailed specification hereinafter following, and by referring to the drawings annexed hereto.

A suitable embodiment of the invention is shown in the attached drawings, wherein:

FIGURE I is a top plan view of a covered vent in the roof of a building with the hinged cover thereover in closed position;

FIGURE II is a cross-sectional, elevational view taken on the line II-II of FIGURE I, wherein one of the spring lever mechanisms for opening the vent cover is shown in full lines, as it would appear with the vent cover closed, and is shown in broken lines as it would appear when the vent cover has been raised by such mechanism; FIGURE III is a cross-sectional, elevational view taken on the line III-III of FIGURE II, showing the attachment of the edge of the vent cover dome under the flashing thereabout, and the seal arrangement for sealing the edge of the vent cover to the curbing about the vent, and further showing the pivotal attachment of the short lever of the spring lever mechanism to one of the channel members extending across the underside of the vent cover;

FIGURE IV is a crosssectional, elevational view taken on the line IV-IV of FIGURE II showing a typical hinge mounting for the lid;

FIGURE V is a cross-sectional, elevational view taken along the line V-Vof FIGURE II, showing the holddown latch-fusible link arrangement for holding the lid closed, and also showing the pull cord extending into the building for manually operating the latch, if desired;

taken on the line VII-VII of FIGURE V, showing the pivotal connection between the bell crank arm of the cover hold-down latch mechanism;

FIGURE VIII is a cross-sectional, elevational view taken on the line VIIIVIII of FIGURE VI showing a typical hinge mounting for the cover;

FIGURE IX is a front elevational view of one of the brackets to which the spring lever mechanism is attached, and showing a front elevational view of the latch for engaging the long link of the spring lever mechanism to automatically hold the lid in raised position:

FIGURE X is a cross-sectional elevational view taken on the line X-X of FIGURE IX showing the resilient bumper for engaging the raising arm of the spring lever mechanism to cushion its upward movement, and showing the latch in engagement with the raising arm of the spring lever mechanism, said view showing the parts in the position in which they would appear with the lid in raised position;

FIGURE XI is a transverse sectional view taken along the line XIXI of FIGURE X showing the latch in engagement with the lifting arm of the spring lever mechanism, and showing the spring which urges the latch into engagement with the arm;

FIGURE XII is a perspective view of the bell crank arm employed in the lid hold down latch mechanism; and

FIGURE XIII is a perspective view of the bracket for such lid hold down latch mechanism.

Numeral references are employed to designate the various parts shown in the drawings, and like numerals indicate like parts throughout the various figures of the drawings.

The numeral 1 indicates a rectangular housing or curbing for the vent assembly, said housing having a laterally extending lower flange 2 thereabout which is positioned about an opening 3 in the roof 4 of a building.

The flange 2 may be secured to the roof of the building by means of a suitable attachment member, such as nails, bolts, or screws 5. The flange 2, after attachment, would be sealed about in the usual and customary manner and overlaid with roofing material as shown.

The cover for the vent assembly is generally indicated by the numeral 6 and may be made of any desirable material. As shown it is dome-shaped and made of transparent, light admitting plastic material, so as to provide light for the interior of the building and at the same time provide a weather-tight cover.

It will be understood, however, that the materi-al of the vent cover may take any suitable form such as metal or composition material, and it may be either dome-shaped, as shown, or flat.

As shown, the dome-shaped cover 6 has an annular flange 6a thereabout, which is overlapped by the inwardly extending flange of a suitable metal flashing strip 10. The inwardly extending flange of the flashing strip 10, preferably has suitable corrugations or knurled surface 10a on the inner side thereof, to grippingly engage the .flange 6a of the cover 6.

The cover assembly includes a rectangular inner frame 7.

A lateral, outwardly extending flange 8 is provided about the inner frame member 7, which is terminated at its outer edge by a downwardly projecting lip 9. The vertical flange of the flashing It} is interengaged with the downwardly projecting lip 9 by means of inter-engaging i diagonally disposed V-slots Itib in the abutting surfaces of the respective members. The vertical flange of the flashing 16* is secured to the downwardly projecting lip 9 by means of screws 10c.

Spacer strips 11 are positioned between the upper surface of the lateral extension 8 and the lower surface of the outwardly extending flange 6a of the cover member 6, and are pressed into engagement therebetween when the respective members hereinbefore described are assembled as shown in FIGURE III.

The spacer strips 11 are spaced apart to provide drainage slots between extension 3 and flange 6a to all w condensation to drain off the inner side of dome 6. Milled slolts (not shown) are provided through V-slots 16b coinciding with spaces between spacer strips 11 to permit drainage of condensation to the outside.

A seal seat flane 12 is secured in overlapping engagement with the side walls of the curbing I and includes a diagonal laterally extending lip 13, providing a flashing for roof parts which might be extended upwardly about the curbing.

A seal strip 14, made of resilient material, is secured to, and disposed about, the upper surface of the seal seat member 12, so as to provide a seal between the cover 6, and the seal seat member 12 when the cover is in closed position, as shown in FIGURE II.

The cover 6 is hingedly attached to one wall of the housing I by means of hinge assemblies at opposite corners, each of which comprises a hinge bracket 15, which is secured to the downwardly projecting lip 9 of the lateral extension 8 by means of suitable screws and nuts 16.

The hinge bars I7 (FIG. VIII) are secured to the Wall of the housing 1 by means of nuts and screws 18, and the outer ends thereof are pivotally attached to the hinge brackets 15 by means of hinge pins 19 (FIG. IV) which extend through passages provided in the outer ends of the hinge bars 17 and are threadedly engaged through the wall of the hinge brackets 15.

It will thus be seen that when the lid 6 is raised the hinge brackets 15 will pivot arcuately upwardly and backwardly as the hinge pins rotate with reference to the hinge bars 17. One of said hinge assemblies, as above described, is positioned adjacent each corner at one side of the vent housing 1.

A bell crank arm 29 is pivotally attached to the front wall of the housing I by means of a pivot bolt 21 which passes through a rotatable bushing 22 (FIG. VII) disposed through a hole 24in provided through the upper end of the arm 29. The pivot bolt 21 is secured to the wall of the housing I by means of a nut 23 threadedly attached on the inner end thereof.

The bell crank arm 2th (FIG. XII) includes an integral right angular arm 24 thereon at the upper end thereof, which has a rounded surface'Z ia on the upper outer end thereof.

A latch bracket 25 (FIG. XIII) is attached to the inner side of the front portion of the inner frame member 7 of cover 6 in position so that the angular disposed leg 26 thereon extends downwardly below the lower edge of the said inner frame member.

The angular leg 26 includes a right angularly turned flange 2'7 thereon which is arranged to engage the lateral arm 24 on the bell crank arm 29, for the purposes hereinafter mentioned.

Holes 2% are provided in the outer end of the bell crank arm 20 which are arranged to be engaged by S- hooks 32a and 28a.

A fusible link 28 is attached to the S-hook 2&1 and the other end of said fusible link is attached to a helical spring 29 by means of an S-hook 28b. The opposite end of the spring 239 has a length of cord or cable 36} secured thereto, which in turn is pivotally attached to the inner side of the front wall of the housing It by means of a pivot bolt 31.

It will be seen that the lateral arm 24 of the bell crank arm 20 may be engaged with the flange 27 of the angular leg 26, and the spring 29 may be stretched to allow the hook 28a to be engaged with one of the holes 20b in the lower end of the bell crank arm 20. The tension thus exerted by the spring, will exert a force between the arm 24 and the flange 27 suflicient to prevent counter-rotation of the arm 20 to allow disengagement of the arm 24 from the flange 27, thereby holding the lid 6 in closed position.

It will be observed that the arm 20 is much longer than arm 24 (by a ratio of approximately 10 to 1), and that the force of spring 29 is exerted at the outer end of arm 20. Therefore, the mechanical advantage is such that a 10 pound force exerted by spring 29 on the end of arm will counteract a force of 100 pounds or less, acting upwardly on arm 24 to thereby hold the lid down.

In actual practice the ratio of length of arms 20 and 24, and the force exerted by spring 29 is such that the hold down force on lid 6 is more than suflicient to hold the lid down against not only the upwardly acting force of the raising mechanism but also added force which might be exerted around the edges of the lid by a wind of storm velocity such as 100 mph. or more. Of course, these forces and relationships can be accurately determined and built into the device.

One of the unique advantages of the hold down mechanism is the ability to adjust the force exerted by spring 29 to exert a desired hold down force for a given installation.

When the fusible link 28 is severed by being subjected to a predetermined heat, the arm 20 will, of course, be released from the spring tension of the spring 29, and the flange 27 will exert an upward force on the lateral arm 24 to cause the bell crank arm 20 to rotate about the pivot pin 21 in a clockwise direction to release the arm 24 from the flange 27 to thereby allow the spring lever mechanism, hereinafter described, to lift the cover upwardly about the hinges therefor.

The above described hold down latch may be released by manual means, if desired. For this purpose there is provided a cord or cable 32 which is attached to the lower end of the bell crank arm 20 by means of the hook 32a engaged with one of the holes 20b. The cord 32 is extended about a pulley 33 attached to the inner side of the housing 1, and is suspended interiorally of the building through the passage 3. An engaging ring 34 is provided on the outer end of the cord 32, whereby same may be grasped and the cord pulled downwardly to exert a lateral force on the outer end of the bell crank arm 20 suflicient to overcome the tension of spring 29 and rotate the arm 20 in a clockwise direction, to release the lateral arm 24 from the flange 27, and thereby release the lid 6 for upward movement by the spring-lever mechanism hereinafter described.

As shown in broken lines at 35, the cord 32 could be extended outwardly through the side of the housing 1 so that the ring therefor would be accessible from the roof of the building so that the lid 6 could be released from the roof.

A spring lever assembly is provided, of which there may be one of more between the housing or curbing 1 and the lid assembly 6, to automatically raise the lid about the hinges therefor upon release of the arm 24 from the latch bracket 25, as hereinbefore described.

Only one of said spring lever assemblies will be de scribed, it being understood that all of the spring lever assemblies employed are duplicates.

Each spring lever mechanism includes a bracket 36 having an inner wall secured to the side of the housing 1 by means of bolt and nut assemblies 38 and 48 (FIGS. a

The bracket 36 includes spaced outwardly extending sides 37 which taper upwardly and outwardly, and the upper ends thereof are disposed near the upper edge of the housing walls.

An elongated lifting arm 39 is pivotally attached at its lower end between the sides 37 by means of a pivot bolt 40. The outer end of the lifting arm 39 is pivotally attached to the lower end of a shorter link 41 by means of a pivot pin 42 pivotally extending through the ends of said links. The pivot pin 42 extends outwardly on each side of the joined links 39 and 41, and the lower ends of the pair of springs 43 are secured to the outer ends of said pivot pin.

The other ends of the springs 43 are hooked in holes provided at the upper ends of the sides 37 of the support bracket 36. a

The upper ends of each of the links 41 are pivotally attached to vertically extending flanges 44a of channel members44. The channel members 44 extend between, and are secured to, opposite sides of the inner frame membtr 7, on which the lid 6 is supported.

The upper end of the link 41 is pivotally attached about a pivot bolt 45', which extends through the flange 44a, a bushing 46, and is secured thereto by a nut 45a threaded on the outer end thereof.

Means is provided for automatically latching the lid 6 in upward position.

Each bracket 36 has a latch assembly associated therewith for latching the lid assembly 6 in upward position, and the description of one such latch assembly will suflice for both.

The said latch assembly includes a latch bracket 47 which is secured to the spring bracket 36 and the wall of the housing 1 by means of bolts and nuts 38 and a bolt and nut 48 which also extends through a bore provided in the rubber bumper 49.

The rubber bumper 49 is arranged to engage the lifting arm 39 to limit the upward movement thereof and to cushion the impact thereof when the lid is opened in the manner hereinafter described.

The latch bracket 47 includes an inwardly extending right-angular flange 50 to which the latch arm 52 is pivotally secured by means of a pivot bolt 51 (FIG. X).

The latch arm 52 has a hook 53 provided on the outer end thereof which is arranged to engage the lifting arm 39 when the lifting arm moves to vertical position. The latch arm 52 is spring urged inwardly by means of a spring 54 which is looped about the pivot pin. 51. The spring 54 has one end turned inwardly and hooked into a bore provided in the outer wall of the latch arm 52 and the other end thereof is engaged against the inner side of the rear wall of the bracket 36 so as to normally urge the latch arm 52 inwardly against the stop 50a, extending from the flange 50.

The operation and function of the device hereinbefore described is as follows:

It Will be noted that with the lid assembly 6 in down position as shown in FIGURE II, the lifting arm 39 is in horizontal position and the spring 43 is extended, thereby exerting an upward force on the arm 39. The lid is held down in closed position by the engagement of the arm 24 on the bell crank arm 20 with. the flange 27 on the bracket 25. The arm 24 is held in engagement with the flange 27 by force exerted on the outer end of the bell crank arm 20 through the tension of spring 29.

Upon the 'fusiblelink 28 being exposed to a predetermined temperature, the same will melt and break, therelby releasing the force exerted by the spring 29 on the outer end of the bell crank arm 20. The force exerted by spring 29 is sufficient to prevent the force of springs 43 from overcoming same and rotating the bell crank arm to release the arm 24 from the bracket 25.

rapidly in response to the relaxing force of the springs 43, and the lifting arm 39 engages the outwardly tapered surface 52a of the spring arm hook 53, moves the spring arm 52 outwardly against the spring 54 and is engaged behind the hooks 53. The lifting arm 39 strikes the rubber bumper 49 to cushion the impact thereof. At this point the lid 6 has been raised by the lifting arm 39, and link 41 is raised to an inclined position, as shown in broken lines in FIGURE II. In such position the lid assembly is locked against downward movement by the latch 52.

In the event it is desired to manually release the arm 24 of hell crank arm from the latch flange 27, the cord 32 may be pulled downwardly by grasping the ring 34, thereby rotating the bell crank arm in a clockwise direction against the spring 29, to release the arm 24 from the flange 27 thereby allowing the springs 43 to raise the lid in the manner hereinbefore related.

In the event the heat is not sufficient, or if the pressure suddenly increases within the building as a result of an explosion, the bell crank arm latch will be released by a predetermined pressure being exerted underneath the cover 6. Such pressure need only be suflicient to overcome the force of spring 29 which will allow the slanted cam surface on the inner side of the flange 27 to Work against, and slide over, the surface on the lower side of the bell crank arm 24, to thereby rotate the bell crank arm 20 in a clockwise direction, to release the arm. 24 from the bracket flange 27, and thereby allow the spring lever mechanism hereinbefore described to lift the cover assembly 6.

Thus the cover 6 is openable either in response to a predetermined temperature, a predetermined pressure, or may be manually released for opening.

It will be observed in FIGURE II, that when the lid is in raised position, the spring lever mechanism is contracted against the inner wall of the housing and extends upwardly out of the housing so that it does not form an obstruction to the passage of heat, smoke and gases through the opening provided by the vent.

In order to reset the lid in closed position, it is brought downwardly, the arm 24 is engaged with the flange 27, and a new fusible link 28 is placed between the spring and the outer end of the bell crank arm 20 to hold the lid in downward position until released as hereinbefore described.

There is shown in broken lines in FIG. V a modified cover hold down ararngement wherein two spaced bell cranks 20a and 20b, are pivotally attached to the sidewall of the housing, each having a lateral arm 24a and 24b engageable with brackets a and 25b secured to the cover.

The lower ends of arms 20a and 20b are attached together by a cord 55. A fusible link 28:: and a spring 29a are attached between the lower end of arm 20b and the sidewall of the housing.

It will be seen that when fusible link 28a is severed by heat, the tension of spring 29a, holding the arms 24a and 24b in engagement with the bracekts 25a and 25b, is released, allowing the arms 20a and 20b to rotate clockwise and release the cover 6 for opening by the spring-lever arrangements hereinbefore described. The brackets 25a and 2519 are identical in construction to bracket 25 heretofore described.

A cord 3 2a extends from the lower end of arm 20a about pulley 33 and may be pulled either from inside the building or the roof to manually release the arms 24a and 24b from brackets 25a and @511.

This dual hold down latch assembly may be required for use on extra size vent cover installations.

It will be understood that preferred emlbodiments of the invention are disclosed herein, and that other and further embodiments may be devised and still come within the scope of the appended claims.

Having described my invention, I claim:

I. In a device of the class described, a housing having upstanding walls arranged to be positioned over an opening in the roof of 'a building or the like; a cover hingedly attached to one of the walls; a bell crank including a longer downwardly extending arm and shorter laterally extending arm, said bell crank being pivotally attached to a wall of the housing opposite the hinged connection of the cover; a bracket attached to the cover having a portion thereon extending below the edge thereof, the laterally extending arm on the bell crank engaging the downwardly extending portion of the bracket; cover hold down means including a spring member and heat responsive fusible member attached together, the said fusible member and spring member being attached between the wall of the housing and the outer end of the downwardly extending arm of the bell crank; a spring lever assembly comprising, an elongated bracket attached to the inner wall of the housing, a lifting arm pivotally attached to the bracket at the lower end thereof, at least one lifting spring member attached between the upper end of the bracket and the other end of the lifting arm, a link pivotally attached to the outer end of the lifting arm and to the underside of the lid at a point between the center line of the lid and the hinged connection of the lid to the sidewall, the spring being of such length with relation to the lifting arm that when the arm is moved to horizontal position the spring is elongated, whereby when the bell crank is released from the tension of the spring engaged therewith by the breaking of the fusible link, the raising spring relaxes to raise the lid.

2. The combination called for in claim 1 wherein a spring urged latch member is connected to the inner side of the housing in position to engage the lifting arm when it is raised by the lifting spring to thereby hold the lid in upward position.

3. The combination called for in claim 1 wherein a resilient bumper member is attached to the inner side of the housing arranged to engage the lifting arm to cushion the impact thereof when it moves to upward position.

4. The combination called for in claim 1 wherein a pull cord is attached to the outer end of the downwardly extending arm of the bell crank opposite the point of attachment of the hold down means, said pull cord being extended about a pulley attached to the inner side of the housing, and being suspended in the interior of a building wherein the device is mounted so that the bell crank may be rotated by pulling upon the cord, to thereby release the lateral arm of the bell crank from the extension on the bracket.

5. A roof vent construction comprising, a housing having side walls; a cover; means for hingedly attaching the cover to one of the sidewalls; elastically retractable means attached between the housing and the cover arranged to exert a force against the cover to raise same when the cover is released; releasable cover hold down means comprising, a bell crank having a long vertical arm and a shorter lateral arm, said bell crank being pivotally attached to the upper portion of the sidewall of the housing opposite the hinged attachment of the cover; a bracket attached to the cover arranged to engage the shorter arm, and means to urge the shorter arm into engagement with the bracket, including elastically retractable means and a heat responsive fusible link connected between a sidewall of the housing and the outer end of the vertical arm.

6. The combination called for in claim 5 with the addition of means to latch the cover in raised position.

7. The combination called for in claim 5 with the addition of a pull cord attached to the outer end of the vertical arm and extending about a pulley attached to a sidewall of the housing, and being arranged to be engaged from below the housing.

8. In a roof vent, a housing having upstanding sidewalls; a cover hingedly attached to one of the sidewalls; a bracket attached to the sidewall to which the cover is hingedly attached, said bracket having spaced outwardly extending flanges thereon; at raising lever pivotally attached at one end between the lower ends of the flanges; a link; an elongated rod pivotally attaching one end of the link to the other end of the lifting arm; .a pair of springs, each having one end pivotally attached to the flanges at the upper ends thereof, and the other ends thereof being pivotally attached to the opposite ends of the rod on the outer sides of the lifting arm and link; the other end of the link being pivotally attached to the cover at a point between the center line of the cover and the hinged connection of the cover to the sidewall; the lifting arm being of such length with relation to the springs that when the cover is lowered and the .lifting arm is in horizontal position the springs are extended to exert an upward force against the cover through the link; and heat releasable means arranged to hold the lid closed against the upward force exerted by the springs.

9. The combination called for in claim 8 wherein a spring urged latch is attached to the bracket between the flanges arranged to engage the lifting arm when it is raised by the springs.

10. The combination called for in claim 8 wherein a resilient bumper is positioned between the flanges arranged to engage the lifting arm when it is raised.

11. The combination called for in claim 8 wherein the heat releasable means comprises a bell crank pivotally attached to the upper portion of the sidewall of the housing opposite the hinged connection of the cover; said bell crank having a long vertical arm and a shorter lateral arm; a heat responsive fusible link and spring attached between the lower end of the long arm and a sidewall of the housing, and a part attached to the cover engageable with the shorter arm.

12. The combination called for in claim 11 wherein a pulley is attached to the sidewall of the housing opposite the sidewall where the fusible link and spring are attached; and a pull cord is attached to the end of long vertical arm, extended about the pulley, and suspended below the housing.

13. A roof vent construction comprising; a housing having sidewalls; a cover; means for hingedly attaching the cover to one of the sidewalls; elastically retractable means attached between the housing and the cover arranged to exert a force against the cover to raise same when the cover is released; releasable cover hold down means comprising a latch member having a vertically 10 extending portion and a laterally extending portion, the vertical portion being longer than the lateral portion; means for pivotally attaching the latch member to a sidewall of the housing; a member carried by the cover arranged to engage the shorter portion of the latch member; heat responsive breakable means and elastically retractable means connected in series and to the outer end of the longer portion of the latch member; and means to anchor the other end of the heat responsive breakable means and elastically retractable means, with the elastically retractable means extended, to thereby exert a force through the shorter portion of the latch member against the member carried by the cover.

14. The combination called for in claim 13 with the addition of means to latch the cover in raised position.

15. The combination called for in claim 13 with the addition of means attached to the outer end of the longer portion of the latch member, and extending below the housing, through which a lateral force may be exerted on the end of the longer portion to manually rotate the shorter portion out of engagement with the member carried by the cover.

16. The combination called for in claim 13 wherein another latch member is pivotally attached to the side wall of the housing; said last named latch member having a long vertical portion and a laterally extending shorter portion; a member carried by the cover engageable with the shorter portion; and a connector member attached between the outer ends of the longer portions of the latch members.

References Cited by the Examiner UNITED STATES PATENTS 1,596,324 8/ 1926 Trood 292-225 1,720,554 7/1929 Johnson 292- X 2,137,751 11/1938 Davis 52-19 2,827,003 3/1958 Stetson 52-72 2,923,226 2/1960 Wasserman et a1. 52-3 X 3,017,721 1/1962 Wasserman 52-1 3,03 6,406 5/ 1962 Wasserman 52-64 3,182,581 5/1965 Von Poederoyen 268-74X RICHARD W. COOKE, ]R., Primary Examiner. R. A. STENZEL, Assistant Examiner. 

5. A ROOF VENT CONSTRUCTION COMPRISING, A HOUSING HAVING SIDE WALLS; A COVER; MEANS FOR HINGEDLY ATTACHING THE COVER TO ONE OF THE SIDEWALLS; ELASTICALLY RETRACTABLE MEANS ATTACHED BETWEEN THE HOUSING AND THE COVER ARRANGED TO EXERT A FORCE AGAINST THE COVER TO RAISE SAME WHEN THE COVER IS RELEASED; RELEASABLE COVER HOLD DOWN MEANS COMPRISING, A BELL CRANK HAVING A LONG VERITICAL ARM AND A SHORTER LATERAL ARM, SAID BELL CRANK BEING PIVOTALLY ATTACHED TO THE UPPER PORTION OF THE SIDEWALL OF THE HOUSING OPPOSITE THE HINGED ATTACHMENT OF THE COVER; A BRACKET ATTACHED TO THE COVER ARRANGED TO ENGAGE THE SHORTER ARM, AND MEANS TO URGE THE SHORTER ARM INTO ENGAGEMENT WITH THE BRACKET, INCLUDING ELASTICALLY RETRACTABLE MEANS AND A HEAT RESPONSIVE FUSIBLE LINK CONNECTED BETWEEN A SIDEWALL OF THE HOUSING AND THE OUTER END OF THE VERTICAL ARM. 